I’m going to install and flash an arch top window with field applied flanges. With field
applied flanges there is often an open corner and to deal with that situation I’ll take
a piece of FlexWrap™, fold it back and pull off half of the release paper and adhere it
to the head and the jamb of the window. Pull off the second piece of release paper. Pull
this down over the back side of the applied flanges to seal that open corner. First thing
we’re going to do is cut the opening out to install and flash the window. With an arch
top window the first cut is a level head cut, followed by the typical I-cut. Cut a vertical
cut down the center, horizontal cut along the sill. And the last cut in the case of
an arch top is, I’ll cut this HomeWrap™ out flush with the rough opening, around the
arch top. Then I’ll fold these in and staple the back side to the trimmer stud. Then I
want to cut a head flap so I can deal with the head flashing details after I install
the window. I’ll fold this head flap up, out of the way temporarily, so that I can
apply the head flashing later. And we make our 45 degree angle typical cut and then a
vertical cut that represents the spring line of this arch. After we’ve cut the HomeWrap™,
the next step is to apply the sill flashing. I’m using six-inch FlexWrap™ and I’ll
peel off the release paper and I’ll eyeball the sides level to get these centered. I want
to apply this so that the back edge is flush with the interior of this rough sill. I work
it right up to the corner, I don’t want to stretch it into the corner. And then up
the jambs at least six inches. Then I’ll take a J-roller, apply good solid pressure
to get full contact on the sill and the jamb. Then I’ll flex the outside corners – a
nice one piece, seamless corner. Then I’ll flex out the other corner, and then I’ll
fold the vertical leg of the sill flashing down onto the wall surface. And once I’ve
got a position, I’ll take my J-roller again, apply good even pressure to get full contact
with the HomeWrap™. Next step is to apply sealant to the back side of the flange before
installing the window. I’m using DuPont™ Residential Sealant and I’m going to apply
an adequate bead of sealant to the jamb flange, the arch top flange, the second jamb flange,
but I’m going to leave the sill flange uncaulked. The next step is to install the window unit.
I’m going to install it level and plumb then fasten it in place. After the window
is installed, I install the jamb flashing using four-inch StraightFlash™. I’ll get
the top adhered, just to hold it in place, then work my way down the window jamb flange,
gradually pulling the release paper off as I go. You want to make sure that this jamb
flashing extends at least to the bottom of the sill flashing. Now use a J-roller to get
full contact onto the HomeWrap™. I’ll apply the second piece of StraightFlash™
jamb flashing to the other side of the window, again just making sure the top is in position.
After I’ve applied the StriaghtFlash™ jamb flashing, I’m going to take a piece
of six-inch FlexWrap™ and roll it back up on itself then pull off about four inches
of the release paper. And I’ll stick this just past the jamb flashing, get the end started,
stuck, and then roll the FlexWrap™ out around the arch radius past the jamb flashing. We
want this head flashing to extend beyond the jamb on both sides. And I’ll take the J-roller,
apply even pressure to get full contact. After we’ve installed the head flashing, I’ll
pull this temporary piece of tape off, fold it down over the opening. Tape the head flap
in place. I’ll put short pieces along the arch top to seal the head flap down. And after
the window is completely installed and flashed, we’ll come back and apply some DuPont™
Window and Door Foam. It’s a low expanding foam and we’ll apply it just in the cavity
to seal the head and the jamb. This is how to install and flash an arch top window with
field applied flanges, using FlexWrap™ to deal with the arch top at the head flange.